1. Technical Field of the Invention
The present invention relates to a sound field control apparatus that can sterically control localization of virtual audio sources in three dimensions.
2. Description of the Related Art
A multichannel audio system that includes a plurality of speakers at all sides in a listening room to reproduce a sound field providing realism through multiple channels has been suggested (for example, see Patent Document 1). In this type of conventional multichannel audio system, a plurality of speakers (generally, four speakers FL, FR, RL, and RR) is disposed in a plane. Therefore, even when the position of a virtual audio source of an audio signal is three-dimensional, it is converted into a two-dimensional distribution and the corresponding signal is distributed to two speakers to localize a sound image as a virtual audio source.    [Patent Document 1] Japanese Patent Application Publication No. 11-46400
However, a sound field reproduced by the conventional audio system provides a two-dimensional sensation different from a real-world sound field. That is, since the height of localization of the virtual audio source is not controlled, there is a problem in that a height sensation of the sound field is almost entirely fixed by a flat level arrangement of speakers.
Surround sound speakers are installed at high positions in addition to the four channel speakers in some recent surround sound audio systems that are on the market. However, these surround sound speakers only output sounds including environmental or background sounds to support the creation of a sound field and do not contribute to localization of an individual virtual audio source.